When producing parts by moulding, it is important to control the demoulding step in order to obtain an intact and homogeneous surface and reduce non-conformities. In particular, hydraulic-setting compositions such as concrete tend to react with the surface of the mould. These reactions tend to lower the quality of the moulded part and the service life of the mould.
In order to resolve this problem, it is known to coat the mould with a formwork removal or demoulding composition. For the demoulding of parts of hydraulic-setting materials, one may use demoulding oils. The film of oil thus disposed on the sides of the mould makes it possible to avoid direct contact between the hydraulic-setting compositions and the surface of the mould, hence protecting the aforesaid surface of the mould.
However, known demoulding oils still have certain disadvantages. In particular, it remains difficult to obtain parts with a homogenous surface appearance. One may in particular observe the appearance of little bubbles on the surface and colour inhomogeneities, as for example whitish streaks or dark rings.
It therefore remains difficult to obtain moulded parts with a sufficiently homogeneous appearance and colour for certain applications, as for example, uncovered linings after formwork removal.